Ing their estebification



Patented May 1, 1928.

UNITED STATES PATENT OFFICE.

HENRI LOUIS BARTHELEMY, OF VERCELLI, ITALY, ASSIGNOR TO RUTH ALDO. COMPANY INC., 0]! NEW YORK, N. Y., A CORPORATION OF NEW YORK.

PROCESS OF SOFTENING FIBERS 0F CELLULOSE ORIGIN WITILA VIEW TO. FACILITAT- ING THEIR ESTERIFICATION.

Io Drawing. Application filed January 27, 1928, Serial No. 249,987, and in France December 29, 1827.

Ever since the acetylation of cellulose has been practised, it has been recognized as ad vantageous to operate on a cellulose which has been subjectedito a certain modification, instead of on cellulose in its customary form.

It ma even be said that a commencement was ma c. with acetylating the hydrocellu-v example accordingtov the French Patent No.

573,739 of 23rd November, 1923, which prescribes the use of formic acid; also the French Patent No. 473,399 of 12th June, 1914, which prescribes a slight preliminary nitration of the cotton.

2. A preliminary mercerization, see the French Patent No. 507,472, filed 16th December, 1919.

3. A controlled preliminary oxidation of the-cotton as proposed by the applicant himself in the United States Patent Application N 0. 209,167 filed on 28th July, 1927 for an Improvement in processes for the esterification of cellulose. 4. Action of sulphuric acid alone; see United States Patent No. 1,546,679 of 14th May, 1919.

By quite a different order of ideas, it has been proposed to treat the cotton by simply soaking it with 10-40% of acetic acid at a temperature below 30 C. The object of this treatment is merely to cause the fiber to swell in the dilute acetic acid formed by the humidity of the cotton (see French Patent No. 596,802 of 28th J uly,'1924).

It has also been proposed, with a similar object, to force a certain quantity of acetic acid through the previously compressed mass of cotton (see United States Patent No. 1,466,401 of 28th August, 1923). Finally, applicant himself, in the first part of hls United States patent application No. 209,161 filed on the 28th July, 1927, for a Process for the homogeneous esterification of cellulose, proposed to cause the vapor of concentrated .glacial acetic acid to pass through the mass of previously dried fibers.

Applicant has ascertained-and this is the object of the present inventionthat the softening of the cuticle or the outer skin and the internal tissue or pith of the cotton fibers can be considerably intensified, and that the duration of'the treatment can be reduced in consequence, by combining with the action of the vapors of acetic acid, the action of a small quantity of a halogen element,

such as clorine or bromine, or one of their reciprocal combinations, such as bromine chloride, BrGl, 10 Aq., iodine trichloride, &c.

This preliminary treatment not only enables the cotton fiber to be more effectually and rapidly penetrated by the acetylating agents (thereby correspondingly diminishing the waste found after acetylation) but the fiber sustains a supplementary bleaching at the same time. Moreover, the presence of a residual halogen in the fiber enables a considerably smaller amount of sulphuric acid to be employed in the acetylation bath, when said acid is used as the catalyzer.

The temperature at which this small amount of halogen element should be allowed to act is an important factor in obtaining good results. The temperature should not exceed 65, and should preferably lie between 20 and 40 C.

The invention may be carried out in the various ways now enumerated, though these are not to be regarded as restrictive.

1. By introducing the halogens, in the form of gas or vapor, into the mass of dry cotton prior to the vaporization or atomization of the acetic acid.

2. By introducing the acetic vapors simultaneously with the introduction of the halogen vapors.

3. By introducing the acetic vapors in the first place, following by the introduction of the halogen vapors in the second place.

4. By vaporizing, atomizing or nebulizing the mixture (in strictly determined proportions) of the halogen element, or elements,

v and the glacial acetic acid. Chlorine combines only very slowly, if at all, with pure acetic acid out of contact with light and in the absence of chlorination catalyzers such as sulphur or iodine, and it is therefore possible to prepare such solutions several days in advance and to keep them in a compara- 1000 kg. of boiled and bleached cotton are trea'tedwith a current of chlorine gas for 15 minutes, the temperature being main- 1 tained between 20 and 22. At the end of thattime'the chlorine in excess is swept away by acurrentfof dry air, after which an equal quantity of 99.4% acetic acid is vaporized through the mass. After leaving to'rest for an hour, the temperature, which has risen to about LO-45, is allowed torecede.

' Esterification isthen performed, preferably in themanner indicated in the United States patent application No. 209,161 or UnitedSta-tes patent application filed this same day'in the name of the same inventor, for Improvement in the esterification of Ewample 93.

100 kg. of'glacial acetic acid (9899.5% strength) and 250 grins. of pure bromine are mixed in an earthenware vessel, said I mixture being afterwards nebulized through 100' kg. of cotton which has previously been raised to a temperature of 42 C. The cotton should be dried beforehand, so as not to eontain more than 1% of natural mois- 1 him.

After cooling down, the acetylation is effected by the known means, in presence, for example, of sulphuric acid.

Example 3.

100 kg. of glacial acetic acid are vaporized, by boiling, into 100 kg. of carded dry cotton which has been previously raised to a temperature of 50 C. After cooling down to 2325, a current of chlorine gas is passed through the mass in such a way as to fix 0.5%, of chlorine,'referred to the weight of. the cotton. This operation is followedby acetylation in known manner.

-I claim A 1. A process for softening cellulose fibers in order to facilitate their esterification, consisting in subjecting the mass of fibers to the combined action of the vapors of glacial acetic acid and an intensifyin ed from the halogen group of elements. I

2. A process for softening cellulose fibers in order to facilitate their esterifieation,con-. sisting in introducing into the mass offibers both halogen vapor and acetic acid va or. 3. A process forfsoftening cellulose fi ers in orderto facilitate their esterification,'consisting in first introducinghalogen vapor into the mass of dry fibers and then vaporizing "acetic acid through the mass.

4. A process for softening cellulose fibers in order to'facilitate their esterificatiomconsisting in subjecting the massfof fibersto the combined action of the vapors of glacial.

acetic acid and an intensifying agent selected from the halogen group of elements,the Y temperature at which the intensifyin agent is allowed to act not exceeding 5. A process for softeningcellulose fibers in order to facilitate their 'esterifi'catiomco'nsisting in introducing into the mass of fibers both halogen vapor and acetic acid vapor, the temperature at which the halogen vapor is allowed to act not exceeding 65 C.

6. A process for softening cellulose fibers in order to facilitate their esterificatiomcon sisting in first introducing halogen vapor into the mass of dry fibers and then vapor izing acetic acidthrough the'mass, thetemperature at which thehalogen vapor is allowed to act not exceeding 65,C. I

7. A process of softening cellulose fibers in order to faeilitate their esterificatiomco'nsisting in nebulizing' through the mass of fibers, after drying said mass and raising.

its temperature to about 42? (3., a mixture of glacial acetic acid and at least one of the halogen elements.

0 agent selecterr 8. A process for softeningcellulose fibers in order to facilitate their esterification,con-

sisting in subjecting the mass of fibers to the T combined action of the vapors of glacial:

acetic acid and at least one of the halogen elements, forthe purpose of softenin both the cuticle and the internal tissue ointly and also fixing in a homogeneous mannerin the total mass of the fibers acetic acid vapors and gaseous halogen adapted to lessen the amount of the cat-alyzer tosbe afterwards employed. v

9. The process of softeningcellulose fibers before esterification, consisting in subjecting them to the action of vaporized glacial acetic acid and a gaseousintensifying agent selected from the halogen group of elements, substantially as herein described.

.10.. The process of softening cellulose fibers before esterification,consisting in subjecting them to the action of vaporized glacial acetic acid and a gaseous intensify ing agent pertaining to the halogen group.

of elements to soften both, the cuticle and the internal tissue jointly and to lessen the amount of the sul huric acid required for the esterification o? the mass.

11. A process for softening cellulose 5 fibers in order to facilitate their esterification, consisting in subjecting the mass of fibers to the combined action of the vapors of glacial acetic acid and chlorine to soften both the cuticle and the internal tissue jointly and to lessen the amount of the sulphuric acid required for the esterification of the mass.

In testimony whereof I affix my signature.

HENRI LOUIS BARTHELEMY, 

